In some battery packs including a plurality of cells, a plurality of cells are aligned in one direction and a restraint force is applied to the plurality of cells. Specifically, the application of the restraint force to the plurality of cells is performed by using a pair of restraint members placed at positions to sandwich the plurality of cells. The restraint force refers to a force which shifts adjacent two cells in a direction in which the cells are brought closer to each other.
Of the plurality of cells, the cells located at both ends in the alignment direction, in other words, the cells in contact with the restraint members, tend to have higher heat radiation than the other cells. The temperature of the cells located at both ends decreases easily than that of the other cells. In this case, the temperature may vary among the plurality of cells in the alignment direction.